The “if” on X11 at this stage is a theoretical obscurity with every modern window manager of note supporting it, with the user being confident that it shall remain stable; on Wayland, the reality is that every single compositor has it's own own, typically unstable ways of doing this, though Sway is the one that is committed to stabilizing it and wants it's way of doing these things to become a standard, but that is of little use when the others are not picking it up.